On another shaving forum, Shave My Face, there has been some discussion over the past year of the possibility that Gary Young, a descendant of the original Simpson family, might make some brushes, hand tying knots with hair said to be close to the vintage Best grade and techniques from years ago. The latest word is that he might have some brushes available in August or September. If you're interested at all in following this idea, you might check out the thread on that forum.
John